It is interesting that you are able to setup and make an FDS run. While FDS might be good for modeling where smoke will travel, i.e. given an event producing x amount of smoke at y temperature, I do not believe it can accurately model the fire itself. I have yet to see an FDS complex fire model that matched tests. I seem to remember published FDS results always tending to be too hot too soon, with a different temp/time profile than the real test burns. The FDS manual even says a true fire is too complex to model. Consultants selling these modeling services do not breathe a word of this nor do they mention the important details, like the simplifications, that go into the model and what conclusions the results may say.
If I understand your model setup right it seems to be a 30x30 room that would normally have four sprinklers in it at 15x15 spacing. (A room size with no sprinkler wiggle room.) There are four clouds in it with eight sprinklers. Four are at the cloud level at 15x15 spacing and four are above the clouds at 15x15 spacing. The steel is 16" beams at five foot spacing (Sheesh, what is all that steel holding up?) and the fire is in the center of the room. The upper sprinkler depth below deck is not mentioned nor is it mentioned if the sprinklers are QR. The fire size is not mentioned. I would think you should run the model without the clouds, but with the steel, and run the model with a true ceiling for the entire space at the cloud elevation. Make these runs using QR and SR sprinklers. For just the steel condition the sprinkler elevations should be where a contractor is likely to install them using the least amount of parts. Additional modeling runs may be necessary to model the upper sprinklers where a contractor is likely to install them using a shared branch line takeoff. I would also think there should be runs where the model is doubled in size to 60x60 where there would be 24" primary beams at the 30 foot mark. In other words the 16" beams frame into 24" beams. All of these runs would be the baseline runs to compare to when running the cloud models. Allan Seidel St. Louis, MO On Aug 11, 2013, at 12:16 PM, Brad Casterline <[email protected]> wrote: > Allan, > > Cloud-no-steel (unobstructed construction): > > DEVICE Activation Times > > 1 CLOUD1 No Activation > 2 CLOUD2 No Activation > 3 CLOUD3 No Activation > 4 CLOUD4 139.6 s > 5 CEILING1 93.4 s > 6 CEILING2 94.7 s > 7 CEILING3 93.3 s > 8 CEILING4 94.5 s > > Cloud-steel (obstructed construction): > > DEVICE Activation Times > > 1 CLOUD1 No Activation > 2 CLOUD2 No Activation > 3 CLOUD3 136.6 s > 4 CLOUD4 No Activation > 5 CEILING1 No Activation > 6 CEILING2 No Activation > 7 CEILING3 No Activation > 8 CEILING4 No Activation > > the description is: &HEAD CHID='cloud', TITLE='8 ft ceiling, 9.375 gap, > cloud cross fast fire, baseline activation'/ > > This is a 30'x30' room with (4) clouds with equal gaps all around and > between clouds and the fire in the middle. CLOUD1 through CLOUD4 are > pendents centered in the clouds and CEILING1 through CEILING4 are uprights > directly above. for Cloud-steel, there are (5) 16" deep beams at 5' C-C. > The 'plenum' space is 24" deep. > The reason I think Dr. Floyd called this 'baseline activation' is because > this set-up allows more of the plume to go up the gap. Since the main > criteria is that the plume activate the cloud sprinklers and not the hot > layer, and if his recommendations were accepted as a ..."reasonable degree > of protection"..., the uprights would not be required, in fact they might > even cause a big mess and delay or prevent the pendent from activating! > To boil this whole thing down to a Standard it makes sense to tie max gap > width to ceiling height. I have not checked the graphics or spread sheets > yet but the only difference I would guess between obstructed and > unobstructed construction above the clouds is a slight increase in the > surface temperature on the top side of the clouds. > > Regards, > Brad > > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
